https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124124
--- Comment #16 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
For reference `check_v3_target_atomic_cmpxchg_word` check if atomic opeations
works on pointer (which I assume are 32bit on the target), and `{dg-add-options
libatomic}` should link libatomic if it is required for 64bit atomic support,
which I think is not handled correctly in this case.
